This invention relates to electrostatographic reproduction machines, and more particularly to a process cartridge for use in electrostatographic reproduction machines. Specifically this invention relates to such a cartridge with automatic camming of a developer module.
Generally, the process of electrostatographic reproduction, as practiced in electrostatographic reproduction machines, includes charging a photo-conductive member to a substantially uniform potential so as to sensitize the surface thereof. A charged portion of the photoconductive surface is exposed at an exposure station to a light image of an original document to be reproduced. Typically, an original document to be reproduced is placed in registration, either manually or by means of an automatic document handler, on a platen for such exposure.
Exposing an image of an original document as such at the exposure station, records an electrostatic latent image of the original image onto the photoconductive member. The recorded latent image is subsequently developed using a development apparatus by bringing a charged dry or liquid developer material into contact with the latent image. A two component and single component developer materials are commonly used. A typical two-component dry developer material has magnetic carrier granules with fusible toner particles adhering triboelectrically thereto. A single component dry developer material typically including toner particles only can also be used. The toner image formed by such development is subsequently transferred at a transfer station onto a copy sheet fed to such transfer station, and on which the toner particles image is then heated and permanently fused so as to form a "hardcopy" of the original image.
It is well known to provide a number of the elements and components, of an electrostatographic reproduction machine, in the form of a customer or user replaceable unit (CRU). Typically such units are each formed as a cartridge that can be inserted or removed from the machine frame by a customer or user. Reproduction machines such as copiers and printers ordinarily include consumable materials such as toner, volume limiting components such as a waste toner container, and life cycle limiting components such as a photoreceptor and a cleaning device. Because these elements of the copying machine or printer must be replaced frequently, they are more likely to be incorporated into a replaceable cartridge as above.
There are therefore various types and sizes of cartridges, varying from single machine element cartridges such as a toner cartridge, to all-in-one electrostatographic toner image forming and transfer process cartridges. The design, particularly of an all-in-one cartridge can be very costly and complicated by a need to optimize the life cycles of different elements, as well as to integrate all the included elements, while not undermining the image quality. This is particularly true for all-in-one process cartridges to be used in a family of compact electrostatographic reproduction machines having different volume capacities and elements having different life cycles.
The step of development or placing the toner particles in contact with the latent image on the photoconductor drum to form the developed image requires that the marking particles or toner be presented to the photoconductive drum. Typically, a donor roll or a roll including a stationary internal magnetic shaft with a rotatable aluminum steel positioned around the outer peripheral of the shaft is utilized to advance the marking particles toward the photoconductive drum.
The spacing between the developer roll and the photoconductive drum surface is important. Spacers placed on the developer roll are often used to ride against the photoconductive surface of the photoconductive drum to maintain an accurate distance between the developer roll and the photoconductive drum. To assure that the spacer remains in contact with the photoconductive surface of the photoconductive drum, preferably, the developer roll is pivotably positioned into contact with the photoconductive drum. A device, usually in the form of a spring, is used to urge the developer roll against the photoconductive drum.
Customer replaceable units (CRUs) which may also be known as cartridges, i.e., process cartridges, are intended to be removed and replaced by a fairly untrained operator of the copy or printing machine. The removal of the CRU and the replacement with a new CRU is intended to be a simple, easy task. Typically, CRU is replaced by first opening a cover or door and then sliding the CRU out of a cradle or location where the CRU fits within the machine. These CRUs are used to interact with the xerographic process and with the paper within the machine. Therefore, CRUs frequently need to be engaged into an operating position within the machine during the installation of the CRU. The CRU thus typically is slid or placed into the opening where it fits and then positioned into an operating arrangement within the printing machine. Typically, the used CRU must first be separated from the components with which it engages and then withdrawn from the printing machine. Similarly, a new replacement CRU must first be inserted into the machine and then interconnected with the operating portions of the printing machine. Such a typical CRU is in the form of a process cartridge.
The process cartridge includes a number of components which have been selected for periodic replacement and typically include the marking particles as well as other components. The process cartridge typically includes the developer roll which is in proximity to the photoconductive drum. The magnetic roll assembly must first be separated from the photoconductive drum and then the process cartridge may be removed from the printing machine. If the magnetic roll is not separated from the photoconductive drum prior to removal, great damage can occur to the photoconductive surface of the drum.
Attempts have been made to provide for the separation of the magnetic roll from the photoconductive drum prior to removal. For example, cranks and levers or knobs are typically used to separate the photoconductive drum from the developer roll within the process cartridge prior to the removal of the process cartridge. The current use of a lever or knob has at least two significant disadvantages. The first of these is that if the lever or knob fails to be properly utilized, the drum may be damaged by the removal of the process cartridge. An additional problem is that the operation of the lever or knob to separate the process cartridge from the drum makes the process cartridge change more time consuming, more difficult, and may require a trained operator to replace.
The present invention is intended to alleviate at least some of the aforementioned problems.
The following disclosures may be relevant to various aspects of the present invention: